Dental casting machine



vJuly 6,1926. 1,591,329

. C. E. LARSON ETAL DENTAL CASTING MACHINE Filed May 7, 1924 :s sheetsfshee 1 @l Q l lb N @I 3/k `3'2 Il@ l l I A Y Z4 Z3 l @I l 5o. z U. l /3 A 2 2f l Ill Il July 6 1926.

1,591,329 C. E. LARSON E T AL DENTAL CASTING MACHINE Filed May 7, 1924 5 Sheets-Sheet 2 l jgp July 6 1926. 1,591,329

c. E. LARsoN Er Al.,

' l'DENTAL CASTING MACHINE Filed May 7I 1924 y 3 Sheets-Sheet 3 jlg-4 Patented July;19126-r ^fj1,591,3297; y 7

' CHARLES E. YMins'onAND- ERIKCK RosENinAKHn-,or Mlimnliroms, lviINNEsomALifj K i DENTAL .CASTINGv1vr -,4iKc'nitIvNrj". if g, K -Applieatimi niet may if; Y1924;` "Ks'eriifivp;rincari;

Our invention provides yasimple and' highsubj'ectfto the'.V meansV forv produclng pneu; K ly eiiicient casting.machineadapted gener-s matic pressure and K j: Q' i 'K i ally for casting bodies of'metalin'to molds Fig.f5 is 'a lview.'Corresp'ending to Fig.: by pneumatic pressure, but 'more especiallyk ,xbntillustratinga modified construction. 5 adapted for use inl casting silver,gold and Describing 4tirstthepreferred construction f 55 ,platinum in making dental castings, such illustratedl i'n Figs. jl -to '4,inclus-ive, theF as inlays, bridges, plates,V crowns and the Vnumeral 6 indicatesanfupri'ght tubularl.l like. The casting 'machineis also ei'ceed- ;framegfcastingsubstantially closedfat its top ingly Kwell adapted for use in castingrings and providedwith a'forwardly p'rojectingL v f Y Y 10 and other articles 'of jewelry. The castingv horizontalKKsfupp'ortingbmket 7;.' An' Oven sog placed inthe ring and-'around the'wax'pat'- lar gassupplyV channelfwhich'flatter will"y "throughout the several views.

y40 improved' casting machine; i

y machine will behereinafter'particularly de- 8, j' shown -'as intheformbf "a rectangular: v 'scribed as used for itsl prim'ary'purpose,'to' j castinggy-is rigidly secured to the lower 'por-v iV wit: for making dental castings. Y 1 tion of thefftubular `trame Gand affords a The pattern "for the; dentalv` casting' is fj portion of thefiame base.;` 'Thisoven'S is 1#curved or otherwise formed inwax andis preferably "provi'ded'jfwith' 'a @separately 65 Y, then mounted on a sprue pin and is thereby' formed oven'` bottom: 9 Kandi with-a door `10.

v'supported onasprue former base. An in As sh'own,"the` bottom plate `9"is provided ves'tment ringis then placed onthe sprue -with acentralair passage lland with small V`former base and' the investment `material is gas burnerlducts 12'that lead from anlannur 0 tern. The investment Aring-is thereafternbe connectedtoa`KKsuitableKgasfsupply, not' K vertedrand, ibytheapplioation fof heat, theV shown. *At its ripper portion, the'oven wax-pattern lis meltedand caused torun out. shown as provided-with a' vent opening 14=LK of the mold. The investment-K'material is VAt` its front,K the frame A'6 is formed withfv formed 'withafcavity affording a rKcrueible, a liatisurface '15 rv'a1'1 d,f at the outer edges 75,1

, .and the bottom 'of thisfis connected. to the thereof, hasrigidly secured parallel upright topf` of the moldby a small sprue. Kv K- l guidev strips 16 that -guide; aj1at plate V17 .K

Ourimproved casting machine is devLtor vertical sliding movementsfSecured' to f signed to take the investment ring, with the the vertically 'movable plate 17 and project-4 mold 'formedas described, and by pneumatic ing'horizontallyforward therefrom is an' in'- 89 pressure, to press thefm'olten metal in the vestment tableLlKS that 'is under. strain to Crucible throughV the Kvsprue vand into: fthe move upwardwith thellplatell'?, this, Klas mold. "The preferred' form of the casting Kshown, being accomplishedfby Vag-weiglit,Il9f f machine and amodiiicKa-tion thereof are il located in the'tubula'r frame; Gffandfconfv lustrated in the' accompanying' drawings, K nected to thevertically'movable plate-17 by B5 wherein like characters indicate like parts;y acable l.2O thatj runs over a guide sheave 21)k 1' Kj journaled.onthe'wtop'of'thejframe. pTl'ie investment table is normally held" showing the downward.4 and: restrained againstfiipward,

Referring to the drawingsz' Fig. 'Kl is a front elevationf Fig. 2 is afragmentary section"takenvafp-y mountedin one of theguide strips"l6,'l`K(sKee i f proximately on the line 2 2 VoflFig.` -l,'""particularly Fig.' 1.)Lf'l`he beveled inner end some parts being removed; K LK' ofthelv'atchKdKog 122 normally engages` the.v

Fig. 3 is a view partly inside elevationgupper edge ofthe'verticallymov'ableplate, v but 'chiefly in verticalsection on the line "17.4 For conveniently moving the'vla'tch dog,'9.5 l 3 3 of Figll; K' J u 22 intov a releasing lposition,there" is pro:l

Fig.4 is a view partly in sidel elevation vided f a finger-actuated tripping j'le'ver'23f and partly in section on the same line as pivoted'to a'projection 'ofKKone' ofithe guide Fig.l K8,`but witlrsome partsf broken away strips 16 and subject to 'a leaf lspri-ngg'24;,4 K and with' the investment table raised 'and' which' latter'normally holds the latch'dog'oo movement" by a 4latch dogj-2K2 slidably 90".

22 in operativel position. Thetable 18 is shown as provided with projecting arms 25 and 26, which'may be conveniently engaged to press the investment table back to its nor- V mal retracted position shown in Figs. 1 and 3, where it will, rof course, ,be held by the dog 22.-.

The Vprojecting upper bracket 'I supports y a depending cylinder 27 and forms theupper head lof: said cylir'ider.;V 'Viorking Ywithin said cylinder is a piston 28, Vwhich is prefer?V ably notonly held normally downwardfby gravity but is also subject to a light coiled.

spring 29. The piston 28has a depending axial, tube '80 to the lower end of which is a sort offsupplemental piston 31 is attached, asshown, byfrthreaded engagement; By reference to. Fig. 3it will be notedI vthat the e lower end ofthecylinder 27 has an inturned stop`- flange that limits thedownward move:l ment of the/piston 28,- and by, ,referencel tov Figa; it will; be notedL that-thesupplementalpiStonSl isof such', size that itl will freely clear, said Vflange '-when moved upward, into thescylinder. Securfedto the lower face-of the.'supplementalpiston 31;,is. a disc'flike Vfacing 32 offsomewhat" flexibleV material, preferably a. felted` fibrous. sheet of-j asbestos. y

'lhefy supplemental; pvistonl'y has aVV central recess 31 and thefacing-32 has air dischargegports 3:9/v that communicate withy said:

' recess. ..7 Y l air'tub'e E53-is securedto. the :head of the bracket 7,a sf.shown,1byga stuffing; box Stand:Y atits outer endisshown asconnected to a` pressurefgauge 3,5and. toa tubular valveu casing,36,;whichlatter, as showmis screwed,

intoy aVVV valve. seat 37. formed in the head of thejbracket, 7' and connected v to, the, interior offthe. cylinder, through anair discharge port 38?. rThe jport 88 is yieldinglyv closed against'lthe,I outflowv of? air from :the cylinder" by,V af, pressurefproducingf valve,.39 that is yieldingly. closed. by f a. spring., 40.'y The. tension of the springAO may be adusted byv a. screwY rod' 41 thatworks with threaded engagementtthroughthe headoftheva'lve cas- Ying: 365 and@ presses .a small follower 42,

againstl 'said spring., At' its. outer, end, thel screw. 41; is provided with a,v graduated head 43 that oo operatess with la.. fixed. pointer 44- onfthe upper endfofftheir said` valvev casing. 'Ehe,head-i'rorming',V portion of" the bracket 7 lisfurther.' providedwith a vent` port t5 thataias.norm-ally1 elcsed` by a; petcock 46,. that Y ispreferably oflthe self-closingftype.-

a.- simple: means for preventing'1 reboundin'gof theinvestment table 18 andthe parts 'carried thereby, ,immediately followingY initial,A contact off the investment, ring with 'Y the facing 32lofthe supplemental piston 31, there, is, provided a spring-pressed retaining dog; 47, shown.aspivotedl to the table 18l at 48 vvs'fith its. upper end'v 'working freely through a slot in said table and subject to a releasing .cani i9 von the inner end of a small rock shaft 50, whichV latter isjournaled to Y flanges on the table 18 and* is provided at its extended end withvan offset finger piece 50. The laterally `eatr-inded lower end of the'dog 47 is preferably serrated and toothed and extendedbeloiv.1 the sliding plate 17 and arranged for engagement with a serrated or line-toothed barl set intoftheflat front lface of the tubular frame 6, in position to be engaged 'by said dog when the table 1.8 is

Crucible; -to'the mold cavity is indicated byv the letter E; and thegold or other material` to be cast is indicated by the ,letter F.` Here it maybe noted that the investment table* 18 is. Vprovided* with a. 4,depressed seat that i'eceivesand quite'closely` fits the lower p0rticn of the investment ringrl and holds the fiaskis vindicated i 'same in axial alignment withV thercylinder i727', main piston 28 and supplemental piston 81,so that when VtheV yinvestment table-'is moved upward, the upper edge ofsaidin-K.V Y vestment ring will be forced 'against the.A

pliable asbestos Vor similar facing 32, Y

Operation., V

vIn the Vuse of` theV casting machine de-l scribed, the moldfcavity, the Crucible-forming cavity, and thel sprue `Will be'forinedv in the investment ring A, as already,indicated'. After thewax model has been mounted yinto` 1 the investment material contained in the investment ring, the sprue pin will be removed, the investment ring will beinverted andY placed in the oven 8 andrtherein sub@ fjected to heat produced by gasflames from the burner passages 12 and the wan model thereby fused and caused to run by gravity y out of thegmold. The 'fused Waxwill, bythe conical upper surface ofthe bottom of the oven, be drainedy out through the ari al pas# sage 11. After thisY has beenrdone, the investment ring will be kagain turned right side up and placedon the vinvest-ment table 18`while the latter is in its lowered position, and'then'the gold or other metal F will VbeV fused by a blow torch `or thelike. T Vhen the metal has been properly fused within the crucible D, ity will,"of course, spread out andv entirely,V cover the sprue E, butV will'. not, under theV action ofV gravity, .runv into the mold.l rEhe investment table is thenreleased by depressing the outer; end of the trip lever 23, which retracts the retaining dog 22, V'and this allows the lweight 19' toV quicklyA raise the investment table the investment:

i ring, VWhen lthe upper edge ofthe, investV the less will 4hethe pressure of the airlon :the-

mentV ring. A is `'pressed against the facing, 32 of the supplemental :piston 131,'the-gpresfev sure fandcontinually actingnforce of. the4 weight 19 willcause the main andlisupple mental pistons to move upward withinftheV cylinder 427, thereby compressing the air'containedlin the latter. lThe fair compressedf within the cylinder finds its escape by rais-z ing the pressure-reducing: valve 39 andpassing through the" casing 36 tothe iaxia'lttube: 33,'sleeve-30,"v cavity land passages 32', vandyinto the Crucible-forming cavityV 2D,

where it exerts 'its pressure on theupper sur-` face of the'molten metalli', and such pres! l Y sure causes'the molten metalto flow down;v y throughthe sprueE and'to'quickly andrcompletely lill the mold cavity C. ',Obvioiusly', the force of the airpressurel on the molten 39, and which action is-regulated by adjustvaries the tension of the spring-40. r @bviously, the greater the tension of the spring' 40 on` thevvalve 39, the less will be theiescape of air through the port 38 and, consetpuently,

molten-,metall The pressureygauge 35'will serve to indicate' thefpressure 'under whichA thevalve 39 operates to vary thegescape of" air and, consequently,"the forceof the air'on the moltenmetal.l i

When the investmentring-'isquiteviof-4 v lentlyv thrown against the 'facing of the sup plem'ental piston, as described, 'the 'airinthe' cylinder will be substantially compressed and'will tend to'react and produce afvibfra`- tion Vordownward movement of the pistonl structurefand such downward'lmovement yto would tend to produce a partial vacuum in f1 the `Crucible D, which would* tend to -draw the jlnolten? metal more orless outofthe mold. In vthe arrangementdescribed, how- V ever, thev retaining dogr 47 ,by engagement l with 'the rack 5l, positively holds" the table" and investment ring to the highest 'posit-ion to whichit'may at any time' be forced, vand:

' this, as is evident, obvi'ates 'the @partial vacuum with tion. c -l/Vhen 'the Vtable linger piece 50 ofthe rock shaft 50, thereby i latch 22. In'resetting-the machine, the-piston shouldbe restoredto normal'position,

the resulting detrimental ac-I f' itwill be'- an easy matter to preset the valvefor the 'predetermined'fdesired.l pressure. t.

` Thestriki-ng plate or supplemental pistonf of theV preferredform ofthe device is spaced* 18V is to be again lowered, it is only ,necessary to press on the oli-'set 'alnl this, i, the; spring 41, 1 assisted gravity, Wi ,1 c is opened.

The Construction:intimated. in Figi is" like thatabovedescribed withthe following exceptions, towit: i in' :this arrangement, the? cylinderf27", which corresponds in most fre-v f quickly accomplish A whenpthe peteocki46.v i i 'spectsto V the cylinder. T27, is `secured to the head-forming portion *#74 'of the bracket pro-F jeoted" from'fthe 'upperv endfof the'v tubular frame 6. Inuthis arrangement', however, a

Ap'istonproper 4isf-notplac'ed'within the cylin der,l but inlrieu thereof-1, thecylinder is providedin vits'upper portion'rwith a` hollowv cylindrical water' container'v y52 .and below- 8f' l.' f

said-container vwith:'an'.'absorbent lpad 53.

preferablyfofffeltediiibrous asbestos. Thev bottomiof the water containerrOjis' providedrv with ya plurality: of `water ldrip` p erfoiationsV y i 54 that will ideliver'wateronto the absorbent pad-53 and fkeepthe same `saturated with normally closed by a removableca-p.

and 'molten :fmetalf'thereiny contained .areforced againstthe water-soakedxpad 53,

steam-,will -belfgenerated y:andthe steaml will 9'53 Y v metal down `into the imold produce the pneumatic' `pressure required to Vforce the vmolten cavitypfy The S-Caiiedintseatreign,fffcourgef 'constitutes `the 'flask' for containing the,` fin-'1 vestment'` ori'nold-forming material.` 1 In thev constructionV illustrated-finFigs@1 to 4,':in

elusive, the "supplemental pis ton head icons. i stitutes ajflask-coveringor 'closing plate',` and l in the construction? illustrated `in I Fig. 5, the

absorbent: materia-l {53 constitutes the' flask' cover ord *closingL plate; Thepressure gauge sh' teach the *operator/'justfthe' setting oftheV the device- *will" i' j Y wn inthe drawings' e Y, may be fleftlpermanently attached to the, de-

Y vice.,y but; `after the needle Lvalve Vhas beenV properly' regulated for different v pr'edete'r-l mined adjustments, lthe gauge may "be: relk moved andg'thepi'pe connection,l from' V'which needlefv'alve required'nto produce pressure Y forv casting a-nyparticular device and, hence,

fromy the mainjbody of -th'epistonl and-is i ctu'in'ecte'dV thereto lonly'fbyfa smallne'ck porcapacity.-V` *This permits fth'e air lto circulate freely aroundor over-fthe supplementalpisl' normally.; holding.r saidf table; depressed and;v

1 for.;` releasing-the. saine aff'. will, and.; an air. discharge; conduitV lea-ding4 from said.; cylfL inder throughY said piston and flaslecover. and arranged: to: deliver.; aine-under. compres-A siony to Ythanflask. When-.the latten. is" moved againstfsaid flaskf Cover. and" Said?.V piston.; iszcaused-tof move upward.. in.. said. cylinder.

- 6:. In ar. Casting. machine., the Combination.,

Y pistnnzfcm .materiallyffexpandedfon; moyableV vertically' on said Vframe and?. 'ari 65 contraetedg. eithenfby lieatjradiatiorr cone- Y duction.

'ciatedif with. said. cylinderg..V tahle located.

belopvisaidrflask coveraandiarranged-toi; carry.

a. flask. against the:V latten, yieldingi.meansn tending'. toi thus; .movev, said: table upward; means` for: restraining; said.;- tablef. againstg suchfI movement. .and for: releasingfthe same atuwill', andimeanszivlierebyaupon. contacto.

the? flask; Witlilsaid-z flask'.y cover;pressure` .Willa-- be; produced fin-r. .said flask .to force; .mo-Iton... metal inter-.az mold: .cavityn-vvithin sa'idzfflaslr.,l

22. Talle; structurezdefined: in, claiinf.. L im Whifihi the-means-z fon movingfsaid table up Wandzincludes a-..weighted cable.;v f

31 s The'. stnuctnret defined iincl'aim'- 1 in.. fur-- r '.ther combination; with a, retainingdogoopf 'eran-ive', tolholdnthe table with@ the flask, in; VContact;.with saidazflask 'cover'l andzagainst etV f 4c. A1 casting.= machine;` comprising.- ahollow'. upright .frameprovidedz With-1 auf. off'setheadfomningzbra'clret,., as cylinder: secured.; to said:

head-forming.. bracket, azflaslr cover asso-,-

ci'atedzwith said cylinderpa `flask/Supportinga,

table..movableavertically.onxsaid .framey andi anran'ged?I toy; position al..flask.. against saidl flask cover. when said vtable -isV moved:l up.;-

' ward; means vfor. holding.I saidf table, Vingja lowered position; andgfrgreleasing the same,

- a@v guide sheavef .oni the; upper portion: of. said.V frame',V `ai cable; VeX-tendediy over" said;V shea-ves. anda. attached, tozsadr r tableg.; said l sheafve at,y itsjother?v endi having2;- Y an;` .attached-.Weight "Wonkingvij Within-.saidf ho'llbvwrama. 5;. Inf. a; 'castinggmaclind the cOmibi nationf.l

with a frame, of an uprightgcylinder sup@ ported in: a. laterally` offsets. position; by,V the y oo ported. in af. laterally. offset. position by@ the;

upper;portionof.said-frame` agnornially .clek pressedrfpiston.v iniy said cylinder.. provided.V 1 ".Withf al flask; Geven; a; flaskfsupporting; table: movable vertically ,l oni said.frame` andV 'arf-.i

ranged Jcozsupport al flask and. to jcarryathe;KV sameagainst said flask.covergyieldingfmeans;' l l f '\vhich. there t is-l a normally closed I airventing; valve. which.; whenl opened. permits free downWardy moyemjevnt ofv said piston, and a.V

Vtending;to,.mo,ve saidl table; upward, means with.`J al,filvaineyv of anjupright. cylinder supfA upper. portiong.of:v Said'v frame. e: Iwrnfwlly` depressed: piston; inf said.. cylinder. provided with: a.. flask. cover, (ai vHaalt-lsu.pnertll.e. table...

11, sei-1532er Y ranged. tov, support. `a flask', and totl carry gthei.

same againstsaid; iiaslf.- cover, yielding` means. tending: to x Vmove'V said? table upward, means',L

normallyzholdingsaid table depressed and fonreleasing vtheisann at Will, andan'yairv discharge'. .conduit'lleading from. said cylin-' denthrough said, piston .and flask: cover and'- arrangedr to deliver .airl under .Compressione further-1V combinationfrwithu an adjustable pressurefproducing valve in said. air delivery e n1duit., the said flaskcover being spaced fir-omi the .piston vproper and' normallyl being;

belowvy saidf cylinder butk freely movablegin 7 In acasting1 machinathe combination- Y with. a; frame, off anrr upright cylinder Vsupported in1 a `laterally offset/ position bythe upper portion of said framasaf normally depressed1.;pist'onin., said cylinder'providedY 'with afiasl. cover, a. flask-supporting ,-table: movable vertically ,on saidrframe and' arf. rangedto Ysupport aliaslfand to carryitheV samef against. saidflask cover., yieldingfmeans tending to; movefsaid table upWard,:means5 normally holding saidtable depress/ed.V and for releasing the sameA at Will.and an vair discharge conduitleading from saidl cylin-A der Ythnouglhi said piston.' and" flask cover and arnangedft'o deliver air under compression. to the flaskA Whenthe latter is moved against saidffl'askg cover andsaidpiston. iscaused to move upward in' said cylinder.andin furj ther. combinationv with` Y an adjustable pressured-producing vvalve vin said air delivery' conduit, thefsa'id. flask" cover being .spaced fromthe; pistonV proper andnormally being. below. saidy cylinder but freely movable in said; cylinder, said flask coverVV havingY a pliable-facing with'centrally locatedair Ypas,v

springt-enclins; wimpel@ downward' movement to ysaid piston.

1Q.f In;v a; casting machine, the combination with. a suitable f-rame'providedY at -itsupper portionA with. an,`Y offset. bracket forming cylinder. head7 a` cylinder secured toand depending from said;V cylinder.V head, af piston vvgorkin'g-V said. cylinder and providedv with a.. flask cover and ag depending tubular stemg ie y of. anair pipe extended axially. through said. Y

cylinder. head!i and telescoped. intofthe; tubular stem.r ofsaid.. pist-0n head, an,v air conduit .1,591,329 Y t l f5 I Y 'A including aV valve casing connecting .the combination with a spring normallyclosing 1 upper portion of saidair pipe to the interior saidpressure reducing Valver a spring teno said cylinder, and an adjustable pression adjusting device including, a screw, a "sure-reducing valve in said valve-casing; graduatedhead secured tosaid vadjusting l- 5v 1l. vThestructure `defined in claim lO inv screw, and a-reletively fixed' 4cooperalting 15 f Y combination with a normallyf'closed agirpointer. y Y *e venting Valve which when opened permits In testinjionjyV whereof we affix our signa# A* `free flow of airinto said cylinder andl free tures. f downward movement of vsaid piston.

CHARLES ELARSON.

'1o 1 12.11116 structure definedine1aim1o`in l n 1f LVERICKROSENDAHL. 

